Exercise treadmills are now widely used in gymnasiums, spas, clinics and in private homes for aerobic exercise, physical examinations and physical therapy, for instance, during recovery from a cardiac illness. An exercise treadmill in its simplest form includes an endless belt that is moved over an underlying support bed, either by the walker's or runner's feet, or by an electrical motor. Not uncommonly, exercise treadmills now employ microcomputers that control the speed of the drive motor, monitor an individual's workout, and provide output displays indicating various conditions, such as time, speed, distance, and calories expended.
To render the exercise treadmill more versatile, it may be positioned at various inclinations to simulate running or walking up a grade. Various mechanisms have been employed to raise the front end of an exercise treadmill relative to the floor or other support surface on which the unit is positioned. For instance, in one type of exercise treadmill, the forward end of the endless belt, associated bed and belt support frame must be manually lifted and engaged with or clamped to upstanding posts. It may not be possible for elderly or physically infirm persons to lift the treadmill belt, deck and frame in this manner. Examples of such exercise treadmills are disclosed in U.S. Pat. Nos. 931,394 and 2,117,957.
In another type of treadmill lift mechanism, the elevation of the forward end of the treadmill is adjusted by manually rotating threaded leg members located at the front corners of the treadmill frame using a wrench or similar hand tool. This method is too slow and cumbersome for most treadmill users. An example of this type of exercise treadmill is disclosed in U.S. Pat. No. 4,151,988.
In a related type of exercise treadmill tilting mechanism, the threaded leg members are trained together by a chain or belt assembly, and a hand crank is mounted on one or both of the legs to rotate the legs in unison. A drawback of this type of elevation-adjusting device is that the runner/walker must leave the endless belt to adjust the height of the screw feet. Also, the drive train components used to interconnect the two screw legs together result in a complicated, heavy mechanism. An example of this type of exercise treadmill is disclosed by U.S. Pat. No. 4,602,779.
In a further type of exercise treadmill, spring mechanisms are employed to carry substantially all of the weight of the forward end of the treadmill frame to provide a substantially "zero-bias" so that the treadmill may be readily raised and lowered to a desired operating position. However, a manually operable clamping mechanism typically must be employed to lock the tilting/supporting means in a desired position. Thus, to change the angle of inclination of a treadmill, the user must dismount the treadmill, move to the front of the treadmill, and reach down to manually operate the locking device. This is not only a cumbersome procedure, but also it may not be possible for elderly or infirm persons to loosen the locking device, lift or lower the treadmill frame, and then sufficiently retighten the locking device to prevent it from shifting during use of the exercise treadmill. Examples of the foregoing type of treadmill elevating device are disclosed by U.S. Pat. Nos. 4,591,147 (assigned to the assignee of the present application) and 4,664,371.
Another common disadvantage of known exercise treadmills, including many of those noted above, is that a substantial number of assembly steps are required, both during the initial preassembly of the machine at the manufacturing location, and also during the final assembly by the ultimate user of the equipment. This is not only time-consuming and expensive, but also oftentimes requires special skills and tools, which many persons do not possess.